Energy storage mechanism for pseudocapacitor

vii LIST OF FIGURES FIGURE TITLE PAGE 2.1 Mechanism of charge discharge process for EDLC 10

2.2 Energy storage mechanism for pseudocapacitor

13 2.3 Common symmetric electrode cell component for ECs 14 2.4 Ragone plot for various energy storage and conversion devices 17 2.5 Timeline of nanocarbon C 60 , CNTs, and graphene research 19 2.6 Schematic of process flow diagram for various electrode fabrication techniques 26 2.7 Schematic of conventional procedure for preparing catalyst nanoparticles or nanoislands and subsequent CVD growth 28 2.8 Simple schematic diagram of CVD technique Azam et al, 2013 31 2.9 ACCVD system ; a Schematic image of current ACCVD system used to grow CNTs and b close-up schematic of sample holder 33 2.10 Preparation of VA-SWCNTs electrode and EC cell assembly. a Images of blank SUS 310S foil and with VA-SWCNTs, b SEM image of VA-SWCNTs electrode. c HR-TEM images of as-grown SWCNTs, d EC cell assembly using two-electrode cell, PP separator, VA-SWCNT electrodes, and [EMIM][Tf 2 N] electrolyte 34 2.11 Growth of aligned SWCNT films after a 15 s, b 1 min, c 3 min, d 10 min, e 30 min, and f 100 min. The scale bar applies to all image 36 viii 2.12 TEM 200 kV image of ‘as grown’ SWCNTs by catalytic decomposition of ethanol over a FeCo mixture embedded in zeolite at 800 °C 37 2.13 Typical Raman spectrum for a CNT sample 38 2.14 CV diagram for EDLC 40 2.15 CV diagram for pseudocapacitor 40 2.16 Galvanostatic chargedischarge curves of as-grown CNTs measured in 1M H 2 SO 4 aqueous solution 41 2.17 Example of galvanostatic charge discharge diagram and the discharge curve exhibit IR drop 42 2.18 Equivalent impedance modeling of the EC 43 2.19 The ESR, Warburg region slope and knee in Nyquist a the semi-circle Curves at high frequency regions, b Warburg region lines slope ~45º known as ‘knee frequencies’ at intermediate frequency regions and c nearly straight vertical lines along imaginary impedance Z image at low frequency regions 44 3.1 Flow chart of experimental 47 3.2 Digital image of blank SUS 310S for the use as current collector in EC 48 3.3 Target material; a Aluminium, b Cobalt 49 3.4 RF-Magnetron sputtering machine 50 3.5 Substrate preparation before deposition was start; a SUS 310S on the substrate holder, b Substrate holder in sputter chamber 50 3.6 Schematic diagram of experimental setup using RF-magnetron sputtering 51 3.7 CNT direct growth electrode process in CVD furnace 52 3.8 ACCVD system for CNT growth 53 3.9 Schematic diagram of experimental setup for ACCVD system 54 3.10 Temperature profile for CNTs growth 54 3.11 EC fabrication using CNTs direct growth electrode 55 ix 3.12 Glove box 56 3.13 Sample preparation for FESEM analysis 57 3.14 Field Emission Scanning electron microscopy FESEM 57 3.15 Transmission electron microscopy TEM 58 3.16 WonATech WBCS3000 Voltammetry system; a Digital image, b Schematic diagram 60 4.1 Cross-sectional FESEM image of a VACNT above the substrate 65 4.2 Top view FESEM image of a VACNT above the substrate at different magnification; a 5 kx, b 20 kx, c 50 kx, d 100 kx 65 4.3 Tilted 45º FESEM image of a VACNT above the substrate at different magnification; a 20 kx, b 50 kx, c 100 kx 66 4.4 TEM image of a VACNT electrode at different magnification; a 120 kx, b 200 kx, c 300 kx, d 600 kx 67 4.5 Conducting paths for electron and electrolyte ion in VACNT electrode 68 4.6 Raman spectrum of CNTs grown on SUS 310S foil 69 4.7 CV curves of as AG-VACNTs electrodes in 1M LiPF 6 measured at 1, 5, 10, 50, 100, 500, 1000 mV s -1 scan rates. Capacitance of the ECs are based on the mass per electrode of the CNTs grown during CVD process 71 4.8 Charge discharge of as grown VACNT capacitor measure at different current; a 1 mA b 5 mA, and c 10 mA 74 4.9 EIS analysis of AG-VACNT using LiPF6 electrolyte; a Nyquist plot showing the imaginary versus real part of impedance. Inset is enlargement of the spectrum in high frequency region, b Bode plot 77 4.10 Heating profile; a CVD process for VACNT growth, b heat treatment process for VACNT electrode using same CVD furnace. 79 x 4.11 CV curve; a CV curve of HT-VACNT and AGVACNT capacitor using LIPF 6 electrolyte at 5 mV s -1 scan rate, b CV curve of HT-VACNT capacitor using LIPF 6 electrolyte at 1,5, 10 mV s -1 scan rate 80 4.12 Charge discharge analysis for comparison of AG-VACNT and HT-VACNT capacitor at 5 mA current; a Charge discharge curve for AG-VACNT, b Charge discharge curve for HT-VACNT 81 4.13 CV curve of VACNT electrode for different electrolyte at 1 and 50 mV s -1 . a LiPF 6 at 1 mV s -1 , b LiPF 6 at 50 mV s -1 , c Polymer electrolyte at 1 mV s -1 , d Polymer electrolyte at 50 mV s -1 . 85 4.14 CV curve of one comb-like VACNT electrode measured at 500 mV s -1 scan rate using three electrode testing system. CV shows upper voltage limit is 3.0 V and a series of lower limits, 2.5, 2.0, 1.5, 1.0, 0.5 V vs. Li in 1M LiPF 6 Chiou et al., 2013 86 4.15 Charge-discharge curve of VACNT electrode for different electrolyte at 5 mA. a LiPF 6 , b Polymer electrolyte 87 4.16 EC cell assembly using different electrolyte; a liquid electrolyte b polymer electrolyte 90 4.17 Thickness dependence of capacitance per area for CNT film comparing liquid electrolyte and polymer electrolyte 91 xi LIST OF APPENDICES APPENDIX TITLE PAGE A Calculation average weight net amount of CNT as active material 108 B Paper Publication: Development of High Performance Electrochemical Capacitor: A Systematic Review of Electrode Fabrication Technique Based on Different Carbon Materials. ECS Journal of Solid State Science and Technology 109 C Paper Publication: Aligned Carbon Nanotube From Catalytic Chemical Vapor Deposition Technique for Energy Storage Device: A Review. Ionic 129 D Electrode Fabrication and Electrochemical Analysis of ACGraphene- Based Electrochemical Capacitor in 1M H 2 SO 4` 154 xii LIST OF ABBREVIATIONS AC Activated Carbon ACCVD Alcohol Catalytic Chemical Vapour Deposition AG-VACNT As-Grown Vertically Aligned Carbon Nanotube CNT Carbon Nanotube CV Cyclic Voltammetry CVD Chemical Vapour Deposition DMC Dimethyl Carbonate EC Electrochemical Capacitor EDLC Electrochemical Double Layer Capacitor EIS Electrochemical Impedance Spectroscopy ESR Equivalent Series Resistance FESEM Field Emission Scanning Electron Microscopy GPE Gel Polymer Electrolyte HT-VACNT Heat-Treated Vertically Aligned Carbon Nanotube MWCNT Multi Wall Carbon Nanotube PVD Physical Vapour Depostion RF Radio Frequency SCE Saturated Calomel Electrode SEI Solid Electrolyte Interface SPE Solid Polymer Electrolyte SWCNT Single Wall Carbon Nanotube xiii TEM Transmission Electron Microscopy VACNT Vertically Aligned Carbon Nanotube xiv LIST OF SYMBOLS µm - Micrometre A - Ampere AgAgCl - SilverSilver Chloride Al - Aluminium Al 2 O 3 - Aluminium Oxide Ar - Argon Co - Cobalt C sp - Specific Capacitance d - EDLC thickness EB- - Electron Beam F g -1 - Farad per Gram Fe - Iron Fe 3 O 4 - IronIII Oxide g - Gram H 2 - Hydrogen HgHgO - MercuryMecury Oxide Hz - Frequency I - Current m - Mass min - Minute mm - Millimetre xv mV s -1 - Voltage Scan Rate N 2 - Nitrogen Ni - Nickel NiO - Nickel Oxide nm - Nanometer O 2 - Oksigen ºC - Celsius Degree Pa - Pascal qa - Anodic Voltammetric Charge qc - Cathodic Voltammetric Charge Rs - Equivalent Series Resistance RuO 2 - Ruthenium Oxide s - Second S - Surface Area of ElectrodeElectrolyte Interface sccm - Standard Centimetre Per Cubic V - Voltage W kg -1 - Power Density Wh kg -1 - Energy Density Z’ - Real Impedance Z” - Imaginary Impedance ε - Permittivity or Dielectric Constant Ω - Ohm xvi LIST OF PUBLICATIONS Manaf, N. S. A., Bistamam, M. S. A., and Azam, M. A., 2013. Development of High Performance Electrochemical Capacitor: A Systematic Review of Electrode Fabrication Technique Based on Different Carbon Materials. ECS Journa l of Solid State Science and Technology , 2, pp. M3101-M3119. Appendix A Azam, M. A., Manaf, N. S. A., Talib, E., and Bistamam, M. S. A., 2013. Aligned Carbon Nanotube From Catalytic Chemical Vapor Deposition Technique For Energy Storage Device: A Review. Ionics , 19, pp. 1455-1476. Appendix B Azam, M. A., Azizan, M. A., Manaf, N. S. A., Izamshah, R., and Mohamad, N., 2014. Electrode Fabrication and Electrochemical Analysis of ACGraphene-Based Electrochemical Capacitor in 1M H 2 SO 4 . Advanced Science, Engineering and Medicine , 6, pp. 1-4. Appendix C Bistamam, M. S. A., Azam, M. A., Manaf, N. S. A.,Goh, P. S., Rashid, M. W. A., and Ismail, A. F., 2014. An Overview of Selected Catalytic Chemical Vapor Deposition Parameter for Aligned Carbon Nanotube Growth. Nanoscience Nanotechnology-Asia , 4, pp. 2-30. Azam, M. A., Jantan, N. H., Dorah, N., Seman, R. N. A. R., Manaf, N. S. A., and Kudin, T. I. T., 2015. Activated Carbon and Single-Wall Carbon Nanotube SWCNT Based Electrochemical Capacitor in 1M LiPF 6 Electrolyte. Materia ls Research Bulletin , 69, pp. 20-23. xvii Azam, M. A., Dorah, N., Seman, R. N. A. R., Manaf, N. S. A., and Kudin, T. I. T., 2014. Electrochemical Performance of Activated Carbon and Graphene based Supercapacitor . Materials Technology . 30, pp. A14-A17. Azam, M. A., Azizan, M. A., Manaf, N. S. A., Izamshah, R., and Mohamad, N., 2013. Electrode Fabrication and Electrochemical Analysis of Carbon Based Electrochemical Capacitor in 1M H 2 SO 4 Electrolyte. Malaysian Technical Universities Conference on Engineering Technology MUCET 2013 . December 3 – 4. Pahang: Universiti Malaysia Pahang UMP. Best of the Best Paper Award Azam, M. A., Jantan, N. H., Dorah, N., Seman, R. N. A. R., Manaf, N. S. A., and Kudin, T. I. T., 2014. Activated Carbon and Single-Wall Carbon Nanotube SWCNT Based Electrochemical Capacitor in 1M LiPF 6 Electrolyte. 6th International Symposium on Functional Materia ls ISFM 2014. August 4-7. Singapore: National University of Singapore. Azam, M. A., Dorah, N., Seman, R. N. A. R., Manaf, N. S. A., and Kudin, T. I. T., 2014. Electrochemical Performance of Activated Carbon and Graphene based Supercapacitor . International Symposium on Advanced Functional Materials ISAFM 2014. August 1-3. Kuala Lumpur: Monash University Malaysia. Azam, M. A, Seman, R. N. A. R., Munawar, R. F., Razak, J. A., Zulkapli, N. N., Bistamam, M. S. A., Talib, E., Kudin, T. I. T., and Manaf, N. S. A., 2014. Carbon Based Electrochemical Capacitor Performance in Aqueous Electrolytes. 3rd International Conference on Design and Concurrent Engineering iDECON 2014 . September 22-23. Melaka: Universiti Teknikal Malaysia Melaka UTeM. Talib, E., Tee, L. K., Zaimi, M., Bistamam, M. S. A., Manaf, N. S. A., Seman, R. N. A. R., Zulkapli, N. N., Azam, M. A., 2014. Electrochemical Performance of Multi Walled Carbon Nanotube and Graphene Composite Films Using Electrophoretic Deposition Technique. 3rd International Conference on Design and Concurr ent Engineering iDECON 2014 . September 22-23. Melaka: Universiti Teknikal Malaysia Melaka UTeM. 1 CHAPTER 1 INTRODUCTION

1.1 Background